The field of the invention is phage display.
Filamentous phage-based display systems (as described, for example, in Smith, Science 228:1315–1317, 1985) have found widespread use in molecular biology, including many immunologic applications such as antigen presentation and the immuno-isolation of desired recombinants by “biopanning” (Marks et al., J. Biol. Chem. 267:16007–16010, 1992; Smith et al., Gene 128:37–42, 1993; Williamson et al., Proc. Natl. Acad. Sci. USA, 90:4141–4145, 1993). However, with filamentous phages, peptides that may be displayed from the major coat protein are limited in size to 6–10 amino acid residues (Kishchenko et al., J. Mol. Biol. 241:208–213, 1994; Iannolo et al., J. Mol. Biol. 248:835–844, 1995), although somewhat longer peptides can be displayed by co-assembly with the wild-type coat protein (Perhan et al., FEMS Microbiol. Rev. 17:25–31, 1995). Full-length polypeptides can be displayed on minor phage proteins, but only at very low copy number (Parmley and Smith, Gene 73:305–318, 1988). Moreover, the requirement that the fusion protein should pass through the secretion system of Escherichia coli may pose problems of toxicity for the host, or for correct folding of the displayed protein (Skerra and Plückthun, Protein Eng. 4:971–979, 1991).